Problem: Simplify the following expression: $z = \dfrac{2}{8a} \div \dfrac{10}{8a}$
Answer: Dividing by an expression is the same as multiplying by its inverse. $z = \dfrac{2}{8a} \times \dfrac{8a}{10}$ When multiplying fractions, we multiply the numerators and the denominators. $z = \dfrac{ 2 \times 8a } { 8a \times 10}$ $z = \dfrac{16a}{80a}$ Simplify: $z = \dfrac{1}{5}$